Not sure I understand your requirement. If you need a column to be fill as you wrote, I could suggest this:
A2 = Unit 1
A3 = A2
B2 = 65
B3 = IF(A2=A1,B1+1,65)
C2 = A2&CHAR(B2)
C3 = A3&CHAR(B3)
Then you can recopy line 3 as you want
Where you want "Unit 2" to start. Just overwrite the formula in column A with "Unit 2".
Hope this will help !
I am wanting to create a custom fill were the series follows an incremental series based an numbers and alphabet characters (Unit 1A, Unit 1B, Unit 1C,....and so on, then the same repeats but starting with Unit 2A, Unit 2B, Unit 2C.....etc.
It is problably a question that has been answered before but I could not find it searching the past threads.
Any ideas would be highly appreciated